Conduct acute (single dose) retinoid toxicity studies in mice at a level of five retinoids per year. Conduct acute (single dose) retinoid toxicity studies in rats on these same retinoid compounds. Conduct 21-day toxicity studies in both rats and mice on these same compounds. In the toxicity studies above, both oral and intraperitoneal routs of administration will be employed. Conduct subacute 12-week studies of retinoid toxicity on the same retinoid compounds as indicated above. These subacute studies will employ the oral route of administration only. Conduct single dose 21-day studies and subacute studies at the number of dose levels indicated in contractor's technical proposal dated June 21, 1978.